Mobile patient monitoring devices (wearable or otherwise) allow patients to have a greater range of mobility. This can improve the quality of care as well as improve patient outcomes. To enable the acquired vital sign data to be monitored at a nurses' station or the like, the mobile patient monitoring device includes a radio providing wireless communication. To provide long battery life, the radio is preferably a short-range radio, which to achieve wider area coverage, communicates with a wireless network typically including access points (APs) distributed so as to provide complete coverage of the hospital floor or multiple hospital floors. The wireless network may, for example, be a WiFi network complying with IEEE 802.11 wireless communication standards. When the mobile patient monitoring device connects to the wireless network, it associates to an AP within the network. As a patient moves around the coverage area of the wireless network, the medical monitoring device's connection to the AP may become weak due to: (1) the distance between the AP and the device; (2) radio frequency (RF) interference between the AP and the device; (3) obstructions between the AP and the device (such as large metal objects, walls, or so forth). When the signal level becomes too low, the mobile patient monitoring device transfers, or “roams” to an available AP with higher power (typically nearer to the mobile patient monitoring device and/or having a less obstructed path to the mobile patient monitoring device). In order to identify available APs, the radio is further configured to scan for available APs and maintain an AP table listing available APs.
Generally, two thresholds of the radio of the mobile patient monitoring device can be configured to influence roaming behavior. The first threshold is a low signal strength scan threshold. When the signal strength of an AP drops below this value, the mobile patient monitoring device will start scanning the environment for available APs. This ensures that for a roam that is likely to happen, the AP table entries in the device are up-to-date. The second threshold is a low signal strength roam threshold. When the signal strength drops below this value, the medical monitoring device attempts to roam to another available AP with higher power.
The scan threshold is used to trigger a scan to update the AP table identifying available APs by signal strength and possibly other factors such as signal-to-noise ratio (SNR). The roam threshold is lower than the scan threshold, and the roam threshold triggers an actual switch (i.e. roam) to a new AP. This two-threshold design reduces radio power draw, since scanning the APs draws significant power.
The following discloses new and improved systems and methods that address the above referenced issues, and others.